The present invention relates generally to mounts for vehicle engines and/or drive trains, and degradation of the elastomeric portions of such mounts due to heat originating from an internal combustion engine or drive train of a vehicle. In particular, the present invention is directed to a thermal isolator that is located between a vehicle engine or drive train and an associated mount.
Increasingly, modern automotive vehicles are incorporating lightweight materials. One reason for this trend is to increase various performance aspects of the vehicle. When used as frame and body members, lightweight materials provide advantages including improved gas mileage due to a reduced overall weight of the vehicle. Until recently, most engines and transmissions have been made of iron and iron alloys. In an engine application, iron components provide strength and other benefits. However, despite engineering challenges, an increasing number of engine and drive train components have been made of lightweight materials, such as aluminum. Aluminum is non-corrosive, lightweight and easily formable into complex shapes. However, compared to iron alloys, aluminum has the property of a relatively high rate of heat transfer.
The higher heat transfer from an aluminum engine can adversely affect some of the components associated with the engine and drive train. In particular, plastic or elastomeric components can be damaged. One component that is particularly vulnerable to being thermally degraded or damaged, is the engine or drive train mount. A typical engine mount includes a metal portion connected to a cradle portion of a vehicle. An aluminum or other similar metal insert of the mount is connected to the engine or transmission. Heat from the engine or transmission can degrade or damage the elastomeric portion of the mount.
As a general solution to degradation from various heat sources, such as reduced airflow to the engine compartment, some prior art mounts include a specially formulated heat-resistant rubber-based material for use as the elastomeric, vibration-absorbing material. Other mounts include a rubber cap, shield or shroud to reduce the effect of heat from the engine compartment. However, these special rubber compounds can have different performance characteristics than presently used elastomeric materials. The shrouds do not address the heat directly conducted to the mount from the engine or drive train component.
Accordingly, it would be advantageous to provide a method and apparatus for isolating the mount from heat directly conducted from an engine or drive train mounted thereto.
One aspect of the present invention provides a thermal isolator including first and second pads, the first and second pads are shaped to cover first and second leg portions of a mount. The isolator further includes a connecting portion attached to each of the first and second pads. The connecting portion is positioned to disconnect when a housing is positioned on the mount.
Other aspects of the invention provide the connecting portion with a friable portion to facilitate disconnection of the first and second pads. The friable portion of the connecting portion can include at least one notch. The thermal isolator first and second pads each include an opening formed therein to receive first and second fastener members. The first and second fastener members can be integral to the mount.
In other aspects of the invention at least one of the openings of the first and second pads has a width less than the width of a corresponding first and second fastener member sized to allow a tight fit of the at least one pad to the corresponding fastener member. The first pad may have at least one tab adjacent the first opening. The tab may be a plurality of tabs on the first pad adapted to engage the first fastener member to hold the thermal isolator in place on the mount. The plurality of tabs can be positioned radially about the first opening.
Another aspect of the invention provides an engine mount system for a vehicle including a mount including first and second leg portions, a first fastener member positioned adjacent the first leg portion and a second fastener member positioned adjacent the second leg portion, a first thermal pad positioned on the first leg portion, the first thermal pad including an opening formed therein to receive the first fastener, a second thermal pad positioned on the second leg portion, the second thermal pad including an opening formed therein to receive the second fastener and a detachable connector attached to the first pad and the second pad.
Other aspects of the invention include an engine mount system where the first leg portion is spaced apart from the second leg portion. The connector can be positioned to break upon positioning of a housing upon the mount. The connector may include at least one notch to facilitate disconnection of the first and second thermal pads. The first and second fastener members can be integral to the mount.
Another aspect of the invention includes a method of thermally insulating a mount from a housing including positioning a first pad on a first leg of the mount, positioning a second pad on a second leg of the mount, and maintaining the position of the first and second pads on the mount prior to connection of a housing upon the mount.
Other aspects of the method of the invention include the first and second pads being simultaneously positioned on the first and second legs. The method may further include receiving a first fastener member through an opening formed in the first pad, receiving a second fastener member through an opening formed in the second pad and connecting a housing to the mount. The first and second legs are permitted to move independently. The opening formed in the first pad has a width less than the width of a corresponding fastener member, and at least one tab formed adjacent to allow reception of the fastener within the first opening.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.